Does post office charge more for mailing a 12 x 9 envelope?

Yes, the post office typically charges more for mailing a 12 x 9 envelope compared to standard-sized envelopes due to its larger dimensions. Postal rates are based on size, weight, and destination, so larger envelopes may fall into different pricing categories. It's advisable to check the specific rates on the postal service's website or at a local post office for accurate pricing.